Currently, Radio Frequency Identification (RFID) systems are being used in various industries to keep stock of items in inventory that are marked with identifying sensors or so-called Radio Frequency (RF) tags. Such systems typically include several RF transmitters placed in locations of interest. An RF tag is placed on each inventory item. The vendor can then successfully track inventory by identifying the presence or absence of an item in a particular location through its RFID tag. By appropriate placement of the RF transmitters, the location of each tagged item is then determined. This conventional system works especially well for inventory items in transit as they are shipped from location to location. RF transmitters appropriately placed, for example, on loading docks, inside a truck, or inside a warehouse can be used to track the status of a tagged item upon purchase to its final designation.
In industries that utilize electronic devices, particularly network service industries, tracking electronic device inventory can be more troublesome due in part to the proximity of the items being tracked. In the telecommunications industry, for example, electronic devices for each node in a network may be installed in adjacent bays or chassis on an equipment rack (frame). Devices that may housed in the same network node include servers, network switches/routers, multiplexers, optical-to-electrical (O/E) converters, and circuit packs. In some cases, it is also desirable to track many of the electronic components within each of these electronic devices, e.g., processors, controllers, memory chips, and the like. The network node itself may occupy a building, or one floor of a building. It is desirable to track not only the location of each device within the network node, but also its disposition in order to distinguish items being stored on a shelf from those which are installed and in use.
It is known that the disposition of an electronic device can be inferred by appropriate placement of an RF transmitter on an equipment rack or live chassis. If the presence of an RF tag associated with a particular electronic device is detected, it is assumed that the device is installed and in use.
In particular, solutions to the problem have been attempted and described in related art, for example, in U.S. Pat. No. 6,847,856 to Bohannon. The Bohannon patent uses multiple sensor pairs to determine the juxtaposition or relative alignment between inventory components. By carefully tracking the physical location of cables using properly placed transmitters and tags, the method determines physical connections between the cables and device ports. Electrical connectivity itself, however, is never verified, but only inferred from the tracked physical locations.
U.S. Pat. No. 6,796,506 to Pradhan, et al., determines the particular location of each tagged electronic device on an equipment rack using a large number of sensors that require careful reader-to-tag alignment. An RF transmitter is placed on each bay of the rack and detects the ID of the tag corresponding to the electronic device installed in the bay. Because the physical location of each transmitter is known, the location of the corresponding electronic device it detects is also known.
Both these schemes can only infer disposition of the tagged devices and do not verify electrical connectivity of the electronic device with the live chassis. In addition, both methods require a large number of carefully aligned sensors in order to detect the location of electronic devices at the rack level. Such an arrangement increases cost due to the large number of sensors required, as well as the cost of installation and continual upkeep.
Because of these costs, the physical location and disposition of electronic devices within a data center or network node are still most commonly determined by manual inventory checks.
There is a need, therefore, particularly in the telecommunications industry, for a method and system for determining the location and disposition of electronic devices within an area in which installed devices are in close proximity to shelved items, such as in a network node.